1. Field of the Invention
The present invention relates generally to antennas and more particularly to slot-coupled array antennas.
2. Description of the Related Art
Slot-coupled array antenna concepts have been described by various authors (e.g., see Zurcher, Jean-Francois, et al., Broadband Patch Antennas, Artech House, Boston, 1995, pp. 45-61). These antenna concepts facilitate the realization of compact antennas that exhibit attractive performance in a number of antenna parameters (e.g., gain, bandwidth, side lobe reduction and cross polarization).
Slot-coupled array antennas, however, are formed with a number of antenna elements which have typically been assembled with costly time-consuming, volume-increasing and/or unreliable fabrication and assembly processes.
As a first example, solder connections have often been used between elements (e.g., feed structure, downconverter, transceiver and external coaxial connector) along a signal transmission path that carries electromagnetic signals to and from the antenna. In addition to being time intensive, the soldering process decreases antenna reliability and the heat of the process may damage or degrade antenna parts. The use of more costly parts has often been required to reduce the possibility of this heat damage.
In a second example, array antenna structures (e.g., upper and lower ground planes) have generally been joined together by adhesives or by the use of a large number of conventional fasteners (e.g., bolts and nuts). These assembly processes are time consuming, increase antenna volume and often form joints that add to the antenna's microwave dissipative and mismatch losses.
In yet another example, flexible transmission circuits have been employed to position external coaxial connectors at a desired antenna location. Flexible circuits typically reduce reliability, require additional space and are expensive.